Dasher PSI & GRT Questions

[FC-Dasher]

I’ve been shooting a Dasher for a number of years, currently on barrel #3, and have had great accuracy and success competing with the Dasher.

That being said, my go to load with 108 Berger’s coated with Tungsten Disulphide (WS2), N140, Tula 556M primers in Lapua BR cases gives me fabulous accuracy and absolutely no pressure signs. I started playing with GRT and entering my components, it shows my load just over 60K PSI, warning that it is over pressure and not to use it. GRT has a max Dasher PSI around 57K PSI.
Since the Dasher isn’t a SAAMI cartridge, there isn’t a PSI ceiling. I scoured the web and found one document from a Quick Load test that listed Dasher’s Max PSI at 65K PSI.

I have no intention of trying to get to 65K, just wondering if somewhere there is an unofficial standard for a Dasher’s PSI limit? Is 57K in GRT just an arbitrary figure in a relatively safe pressure zone? Thanks.

 

[John Glidewell]

My QL has it at 65k psi max

 

[03machstock]

Can’t answer your question on dasher pressure, but in GRT it’s important you use measurements from your actual components and input them such as brass volume, bullet length, etc. as they will probably be different from the standard values from the program, and will effect its predictions.

 

[FC-Dasher]

Glad to see QL at 65K. I could go through the check list of pressure signs and I don’t show a one. Although not a moderate load, it’s not unsafe.
I run a MAC and have to dance around to get GRT to run, it does, but I’m sure there are some entries that I’m missing. I need a real tutorial on how to use that software. I find the interface a bit chunky and difficult to navigate. I don’t see any consideration for coated bullets, there is one area that might apply, but nothing to give a specific value to WS2, Moly or whatever. Thanks for your comments.

 

[45-90]

I run mine at the full 65,000 psi, if I want.
I use Alpha brass, 28" barrel.
Run a lot of normal loads in the 2950 to 3030 fps with match bullets.
But also run 115 DTAC s to 3020 fps, 110 SKM to 3085 fps, 107s to 3133 Ave fps.
The 110 SMK is a favorite at 3085 fps.
It only cost me a barrel blank to rebarrel, so I'm not concerned with barrel life...others however may be. So slow it down a bit...it's a Dasher it will shoot accurately with different components and velocity nodes.

 

[FC-Dasher]

I’m running a 28” barrel too, my load was 2950 from my previous 30” with naked bullets, coated bullets and 2” shorter took a little velocity, now at 2900 fps. But, accuracy is so good, in the 1’s, that I can’t complain.
Reading a lot of posts it appears that many people are shooting their Dasher’s a bit slower, almost down in the BR range.
I shoot F Class Mid and Long Range, 800 yards in I can stay with anyone, but beyond that, those big 7mm’s hold quite an edge. If I get good conditions, I’ll do ok, if not I struggle a bit. But it’s still fun.

FWIW, at a recent 1000 yd match, ShotMarker had my velocity at the target at 1450 fps, a few guys shooting 7-6.5 PCRW’s, their 180 grain Bergers were 1825 fps at the target. Hard to keep up with those numbers. They won it all, 1st, 2nd and 3rd place, good shooters to boot.

 

[45-90]

According to ballistics a 6 dasher at 3085 fps with 110 gr SMK crosses the 1000yd line at 1735.4 fps, at 1500 ft elevation 59° etc. ....Pretty close, with almost zero recoil in a heavy rifle.

 

[RegionRat]

Just remember to keep in mind the pressure you would need to get that 110 SMK up to 3085 fps.
You know ye olde saying... there is no such thing as free lunch....

It takes roughly an increase of 10 ksi to increase velocity from 2850 to 3000 fps with a 30" bbl.
While the 2850 pressure is casual for the brass, stepping on it to go to 3000 fps means you are redlining the pressure.
Safety first. YMMV

 

[45-90]

You can do almost the same with the lowly 308 Win. Lapua brass, built in a long action 30" Palma barrel 5R 8 twist.
The 200 SMK at 2856 fps ave hits the 1000yd line at 1750.2 fps, same ballistics criteria ...so again not much difference than the new calibers, and one of my favorites for the 308.

 

[Doom]

With wildcats there is no standard. The GRT max is probably taken from the 6BR-Norma which is the parent case. The 65KSI in QL is probably what experience and testing has demonstrated.

 

[FC-Dasher]

In GRT, is there an entry for a value for coated bullets? It seems to me that should factor into the cartridges overall PSI. Thanks.

 

[45-90]

In GRT, is there an entry for a value for coated bullets? It seems to me that should factor into the cartridges overall PSI. Thanks.

QL has coating value plus several others , FMJ, solid copper, lead, jacketed, etc.
The start pressure is higher or lower depending on the type of bullet or coating as the bullet engages the rifling, where pressures can spike in a millisecond.
On coated bullets friction is a bit less so velocity will sometimes be a bit lower..so add a fraction of a grain of powder to get the same velocity in smaller csses, or more powder in larger cases.

 

[45-90]

When dealing with wildcats, the parent case would be a strong indicator as to the maximum pressure the case was designed to handle....also the type of action that the wildcat is going into, lever, break open, auto loading, or bolt action and is it modern, old, or noted as weak.
Maybe old outdated cartridges fall into wildcat status because there are no brass cases available, but can be machined out of existing cases.
Is it a black powder rifle or in the newer smokless era with nickel steel barrel?
Strong case weak action is okay just respect the actions pressure limits.

 

[45-90]

For those concerned about pressure, and who isn't? But today's reloaders have an abundance of powder and bullet choices along with software programs, that make things interesting.

Check out the Ultimate Reloader series of 2 videos where Alpha Munitions and BAT actions get together, and run to extreme pressures. First one was predicted over 100,00 psi the second video had more advanced equipment for measureing pressure, and running over 86,000 psi.
In a BAT action of course.
The videos Called "Don't Do This At Home"
Alpha munitions said yrs ago their brass will handle 70,000 psi. So for yrs I run a bunch of high pressure loads along with standard loads through the Dasher with no ill effect, except most likely some barrel life, but I do my own barrel chambering, with my own finish reamer, so barrel life is not much of an issue for me.
Others not so much.
Not recommending this as the "don't do this at home", title suggests.
But its interesting and seeing these manufacturers improving their products for all reloaders and shooters...and giving the adventurous as well as others, a new margin of safety.

 

[FC-Dasher]

45-90, thanks for your insight on GRT and pressure issues and calculations. It is much appreciated, thanks.